Pneumatically operable, fastener-driving tools are of course well-known in the art and are exemplified by means of the pneumatically operable, fastener-driving tools that are disclosed within United States Patent Application Publication 2006/0016845 which was published on Jan. 26, 2006 in the name of Ishizawa et al., and United States Patent Application Publication 2004/0188488 which was published on Sep. 30, 2004 in the name of Ishizawa et al. Both of the aforenoted pneumatically operable, fastener-driving tools basically comprise substantially the same operational components, such as, for example, a cylinder, a driving piston movably disposed within the cylinder, a source of compressed air for acting upon and moving the driving piston downwardly through a fastener-driving stroke, and a vertically oriented driver blade which is fixedly mounted upon the movable driving piston so as to project downwardly beneath the piston in order to be in position to engage a fastener and thereby drive the fastener outwardly from the tool when the driving piston is moved downwardly through its fastener-driving stroke. In addition, various seal mechanisms are incorporated within the outer peripheral edge portions of the driving pistons so as to operatively engage and cooperate with the internal peripheral wall portions of the cylinder in order to effectively pneumatically separate and seal off the oppositely disposed sides of the driving piston from each other. While O-ring type seal members are often used as such seal mechanisms, O-ring type seal members must be constantly biased into engagement with the internal peripheral wall portions of the cylinder in order to perform their sealing functions, and accordingly, such O-ring type seal members experience relatively rapid and significant wear which, of course, in turn, causes such seal members to exhibit relatively shortened service lives requiring maintenance to be performed within relatively shortened periods of time.
An alternatively configured seal mechanism, which has been used within various pneumatically operable applications or systems, is disclosed within FIG. 1, and it is to be noted that such drawing figure substantially corresponds to a drawing which appears within a product manual which is entitled K-Seal™ and which is published by the MICRODOT corporation of Greenwich, Conn. More particularly, it is seen that a pneumatically operable system cylinder is disclosed at 10, and that a piston 12, mounted upon a piston rod 14, is movably disposed within the cylinder 10. The cylinder 10 comprises an internal peripheral wall structure 16, and it is seen that the piston 12 comprises a pair of axially spaced annularly recessed portions 18,20 within which a pair of axially spaced annular seal mechanisms 22,24 are respectively disposed. Each one of the annular seal mechanisms 22,24 has a substantially V-shaped cross-sectional configuration, however, it is to be appreciated that in accordance with the usage of such annular seal mechanisms 22,24 upon the piston 12 within the pneumatically operable system, the upper one of the annular seal mechanisms 22 is oriented in such a manner that the substantially V-shaped cross-sectional configuration thereof is oriented upwardly, whereas, conversely, the lower one of the annular seal mechanisms 24 is oriented in such a manner that the substantially V-shaped cross-sectional configuration thereof is effectively inverted so as to be oriented downwardly.
Accordingly, when the pair of substantially V-shaped seal mechanisms 22,24 are respectively disposed within the pair of axially spaced annularly recessed portions 18,20 of the piston 12, and are disposed so as to have their aforenoted orientations, the pair of substantially V-shaped seal mechanisms 22, 24, when effectively considered together, have a resulting composite cross-sectional configuration that resembles the letter K, as can be readily appreciated from FIG. 1, and hence, the aforenoted reference to the seal mechanism as a K-Seal™. It can be readily appreciated, however, that while the dual seal mechanism system of MICRODOT performs satisfactorily regardless of the direction in which the piston 12 is being moved, the dual seal mechanism system of MICRODOT nevertheless does require the use of a pair of the seal mechanisms 22, 24. Under certain circumstances, or more particularly, in connection with the implementation of certain operating systems, such as, for example, portable pneumatically operable tools, relatively small size and compactness are desirable objectives. Accordingly, such a dual seal mechanism system, entailing such a relatively large axial dimension or extent in order to in fact accommodate both of the axially spaced seal mechanisms, would not be practical.
It is noted that the aforenoted X-Seal™ product manual makes reference to U.S. Pat. No. 4,089,533 which issued to Knudson on May 16, 1978. More particularly, as disclosed within FIG. 2, which substantially corresponds to FIG. 1 of the aforenoted patent to Knudson, a pneumatically operable application or system comprises a cylinder 1 having a cylindrical body 3 and a pair of end caps 5, 7 fixedly mounted within the oppositely disposed ends of the cylindrical body 3. A piston 9, fixedly mounted upon a piston rod 11 which extends through an opening 13 defined within the end cap 7, is adapted to be movably disposed within the cylindrical body 3, and it is seen that the end cap 7 is also provided with an annular groove 25 within which an annular seal ring 23 is disposed for sealingly engaging the piston rod 11 as the piston rod 11 moves within the opening 13. Ports 29,31 are provided within opposite ends of the cylindrical body 3 for admitting and exhausting air into and out of the cylindrical body 3 in connection with the movement of the piston 9 within the cylindrical body 3, and in connection with the movement of the piston 9 within the cylindrical body 3 and with respect to the inner peripheral wall portion 15 of the cylindrical body 3, the piston 9 includes an annular groove 19 within which a single annular seal ring 17 is disposed for dynamically engaging the inner peripheral wall portion 15 of the cylindrical body 3. More particularly, as can best be appreciated from FIG. 3, which substantially corresponds to FIG. 5 of the aforenoted patent to Knudson, it is seen that the annular seal ring 17 is disposed within the annular groove 19, the annular groove 19 comprises a radially inner annular wall portion 21, and the annular seal ring 17 comprises upper and lower end faces 33, 35. Still yet further, the annular seal ring 17 is seen to comprise an outer peripheral wall portion 39, and a radially outwardly flared, flexible lip portion 41 is integrally connected to the main body portion of the annular seal ring 17. Still yet further, the radially outwardly flared, flexible lip portion 41 of the annular seal ring 17 comprises a free end tip portion 49, and that the free end tip portion 49 effectively forms a dynamic interference seal with the inner peripheral wall portion 15 of the cylindrical body 3.
Accordingly, while the aforenoted patent to Knudson discloses the use of a single seal member 17, similar to one of the seal members disclosed within the MICRODOT product manual and having substantially the same V-shaped cross-sectional configuration, it is respectfully submitted that the single seal member 17 will not in fact be properly operable so as to achieve the desired sealing functions during both of the reciprocal movements of the piston 9 within the cylindrical body 3 and with respect to the inner peripheral wall portion 15 of the cylindrical body 3. More particularly, in accordance with the disclosure, principles, and teachings of the Knudson patent, and as has been noted hereinbefore, the ports 29,31 are provided within the opposite ends of the cylindrical body 3 for admitting and exhausting pressurized air into and out of the cylindrical body 3 in connection with the movement of the piston 9 within the cylindrical body 3. Specifically, the pressurized air, having a sufficiently or relatively large predetermined pressure value, acts within the forwardly disposed void region 59 of the seal member 17 so as to effectively force the radially outwardly flared, flexible lip portion 41, and the free end tip portion 49 thereof, into dynamic engagement with the inner peripheral wall portion 15 of the cylindrical body 3 during, for example, the downward movement of the piston 9 as viewed within FIGS. 2 and 3. However, this same sufficiently or relatively large predetermined pressure value will likewise act upon the back or rearwardly disposed side of the radially outwardly flared, flexible lip portion 41 when, for example, the piston 9 is being moved upwardly as viewed within FIGS. 2 and 3. Under such circumstances, it would seem that the radially outwardly flared, flexible lip portion 41 would be moved radially inwardly away from the inner peripheral wall portion 15 of the cylindrical body 3 whereby the sealing properties of the seal member 17 will effectively be compromised.
Accordingly, a need therefore exists in the art for a new and improved pneumatically operable fastener-driving tool and seal mechanism assembly wherein only a single seal mechanism, which is structured so as to exhibit an enhanced service life as compared to other conventional seal mechanisms previously employed within pneumatically operable fastener-driving tools, can be utilized within the pneumatically operable fastener-driving tool, wherein only a single seal mechanism, which is structured so as to nevertheless perform its sealing functions within a pneumatically operable fastener-driving tool, particularly during the differently pressurized operational cycles characteristic of such pneumatically operable fastener-driving tools, can in fact be successfully utilized, and wherein only a single seal mechanism needs to be utilized within a pneumatically operable fastener-driving tool so as to effectively render the pneumatically operable fastener-driving tool relatively small and readily portable.